强磁场对Mn-Sb包晶合金相变及凝固组织的影响

以Mn-56.5 wt%Sb包晶合金为研究对象, 进行了不同磁场、不同冷速条件下的凝固实验. 通过对液相线温度、包晶温度的考察, 发现强磁场可以提高Mn-56.5 wt%Sb合金的液相线温度, 且该上升值随磁感应强度的增加而增加, 当所施加的磁感应强度为11.5 T时, 液相线温度升高大约3 ℃, 但施加磁场后包晶反应温度没有明显改变. 对该合金的凝固组织进行定量金相分析发现, 施加磁场后MnSb相明显减少, 该结果与磁场对相变温度的影响相一致. 另外通过X射线衍射分析发现, 强磁场诱发包晶反应生成相MnSb的c轴垂直于磁场方向取向, 而Mn₂Sb相的(311)面平行于磁场方向取向. 对不同冷速凝固的Mn-56.5 wt%Sb合金组织进行定量金相分析结果显示, 强磁场对合金凝固过程的作用效果受到冷却速度的影响. 随着冷却速度的增加, 强磁场对该合金凝固组织中MnSb相的相对含量变化影响效果减弱. 关键词： 强磁场 包晶合金 凝固 相变温度

Influence of high magnetic fields on phase transition and solidification microstructure in Mn-Sb peritectic alloy

In recent years, the application of high magnetic field in material processing has received much attention from many researchers. However, most studies focus on single-phase solidification or eutectic solidification. The effect of high magnetic field on peritectic alloy is rarely reported. In this study, the solidification experiments on a Mn-56.5 wt%Sb peritectic alloy are carried out under high magnetic fields up to 11.5 T. According to the temperature curve recorded during solidification, it is revealed that high magnetic field increases the liquidus temperature and this rise increases with magnetic flux density increasing. The liquidus temperature rises by about 3 ℃ when the magnetic flux density is 11.5 T. On the contrary, no obvious change in peritectic temperature is found. In addition, the solidified microstructure is analyzed by quantitative metallographic analysis and the result shows that the amount of MnSb phase decreases markedly by the application of high magnetic field. This result consists with the change of phase transition temperature. By the X-ray diffraction, it is found that the c axis of MnSb crystal and (311) plane of Mn₂Sb are perpendicular and parallel to the direction of high magnetic field,respectively. Furthermore, the solidification experiments with different cooling rates are also carried out. The quantitative metallographic analysis reveals that the effect of high magnetic field on solidified microstructure is affected by cooling rate. With the increase in cooling rate, the effect of high magnetic field on the fraction of MnSb phase fraction is weakened.
Keywords： high magnetic fields peritectic alloy solidification phase transition temperature